How temperature stable is Varget REALLY?

223submoa

223submoa

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I have a .308 Remington 700p in an AICS chassis with a Bushnell ERS 3.5-21 mounted on top. I did an OCW test in the winter when it was around -10C. Using 155gr scenars in lapua brass with federal primers and varget I came up with a load of 45.5gr that was very accurate as far out as I tested it (300 yards). It was pretty consistently printing 1/2 moa 5 shot groups at 100 if I did my part. Life got busy for a bit and I didn't shoot much until the last couple of weeks, and this load is not shooting accurately at all. 1.25 inches is about the best I can muster at 100 yards. I'm by no means a pro level shooter, but my abilities are better than that. So I'm wondering if the +- 30C degree temperature difference might be the culprit. I know Varget is touted as being quite temperature stable, but I wanted to get some first hand experience. Have any of you experienced anything like this with Varget? Thanks in advance.

Mike
 
Shouldn't be the powder, IMO.

Remington/DuPont setup the powder plants in Australia (which is now ADI) and sells powder to Hogdon's. The Australian military requested ADI to make their powders more temperature stable for use at home and abroad. These powders are all single base powders and extremely temperature stable as required by the Australian military.

In Iraq and Afghanistan the US military had to switch from double base powders to single base powder for their long range sniper ammunition. The special long range 7.62 ammunition was changed from RL-15 to IMR-4064 powder due to temperature problems with RL-15. Varget and 4064 are single base

If you want to know how stable ADI powders are ask the Australians, they have some of the most extreme temperatures on our planet.

But it's not absolutely immune to temp change, as in none whatsoever. Varget will change fps slightly though with temperature changes. You should get about a 47-61 fps difference at a 30 degree Celsius swing (30C = 86F, then .55-.72 fps per degree F, as per my software). I don't think that's enough to account for the variance in accuracy.

In my (limited compared to others here) experience, I've never experienced the kind of shift you're writing about in any of my rifles that I load with Varget; summer or winter (brass, primers and projectiles being equal)
 
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Melnibonean said:
Shouldn't be the powder, IMO.

Remington/DuPont setup the powder plants in Australia (which is now ADI) and sells powder to Hogdon's. The Australian military requested ADI to make their powders more temperature stable for use at home and abroad. These powders are all single base powders and extremely temperature stable as required by the Australian military.

In Iraq and Afghanistan the US military had to switch from double base powders to single base powder for their long range sniper ammunition. The special long range 7.62 ammunition was changed from RL-15 to IMR-4064 powder due to temperature problems with RL-15. Varget and 4064 are single base

If you want to know how stable ADI powders are ask the Australians, they have some of the most extreme temperatures on our planet.

But it's not absolutely immune to temp change, as in none whatsoever. Varget will change fps slightly though with temperature changes. You should get about a 47-61 fps difference at a 30 degree Celsius swing (30C = 86F, then .55-.72 fps per degree F, as per my software). I don't think that's enough to account for the variance in accuracy.

In my (limited compared to others here) experience, I've never experienced the kind of shift you're writing about in any of my rifles that I load with Varget; summer or winter (brass, primers and projectiles being equal)
Click to expand...

Wow that is some interesting information. Thank you. I'll have to look at some other things then. I'll tear the rifle down and make sure nothing is loose. I have some other loads for this rifle that have shot well in summer before, so maybe I'll sit down at the bench and put some together.
 
Not to slag your shooting, but my ability varies. Sometimes i am in a hurry/try to squeeze in range time.....never works out. Another thing i find is that my shooting is much better if i lay off the DD at Timmys.....caffeine....for three days.

My bet is still part temp sensitive, part indian, very little arrow.
 
nowarningshot said:
Not to slag your shooting, but my ability varies. Sometimes i am in a hurry/try to squeeze in range time.....never works out. Another thing i find is that my shooting is much better if i lay off the DD at Timmys.....caffeine....for three days.

My bet is still part temp sensitive, part indian, very little arrow.
Click to expand...

Anything is possible. I can usually tell if I've pulled a shot before I even get back on target, and I shot a few groups yesterday that I felt should have been pretty good.
 
Last year while doing a load with my 223 using varget. Its only changed like 6-7 fps from like -5 to +25, so I disagree that it swings that much.
 
I know that at 40 below Varget gives up all sorts of speed. By the time it warms up to a balmy -20 it isn't that bad, and things returned to sanity around zero.

I had to work up 30-06 loads in Canada at -40 to load and use in Australia at +40. The 165 grain loads that moved right along at 2900 in normal temps chugged along at 2650 at 40 below. The only consolation was that everything else I tried was worse. I got to test Korths patience as they cut me a new CDS every time it warmed up.��
 
Try shooting with the coat you were wearing when it was -10 out.

Might be something as simple as how the rifle was "fitting" you with an extra inch or so of padding at the shoulder...
 
Varget is stable and should not have tripled your group size.

That being said we can try and eliminate some variables. any chance you chrony'd your speed during your first OCW (winter) if so check the speed today to compare numbers.
Component changes can make a huge difference...did you change any part, even different lots of the same item have noticeable changes... I have to re-test when changing primers of different lots.

Did you make these loads in the winter and are shooting them now? less likely but possible is that the bullet has cold welded changing neck tension.

Gun related can you tighten/check all your bolts and screws...peace of mind

All the best
Trevor
 
Never an issue with Varget and I use it year round in several calibers.

Shooting is a perishable skill with a relatively short shelf life if you lay off for awhile.
 
Three factors have the largest effect on group size, in varying order.
Shooter-gun-ammo.

Scopes and mounts are included with the gun factor.
 
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